Various capacitive torque and force sensors are known in the prior art. In the industrial sector, torques are today generally measured with measuring cells which are fitted with strain gages. Strain gages are attached directly to the measuring point on a structural element. However, the adhesive attachment and contacting of strain gages proves to be technologically difficult. This is disadvantageous in particular in the case of mass production and applications in the field. Furthermore, the long-term stability and overload resistance of strain gages are not satisfactory.
Other known capacitive torque and force sensors have, for example, electrode structures that engage in one another in a comb-shaped manner. The displacements occurring in these cases are only a few micrometers. The electrode spacing is thereby altered in a way corresponding to a displacement at the measuring site. Although it is less problematical to attach sensors of this type to structural elements on which measurements are to be taken, a very high degree of accuracy in the interspacing and adjustment is required in the production of comb structures. This limits the possibility for cost reduction.
The invention is based on the object of providing an integrated capacitive microsystem which can replace previous sensors, is much easier to attach and has greater endurance and improved overload resistance.
Furthermore, a modification for use on vehicle seats and an operating method are to be specified.
The solution achieving these aims, on which the invention is based, is respectively obtained by the following:                A capacitive microsystem for recording mechanical deformations comprising:                    at least two flat electrodes set at acute angles with respect to each other, said electrodes comprising a measuring electrode and a counter electrode, wherein measuring signals result from changes in the capacitance when there is a corresponding change in the setting angle formed between the electrodes;            an elongate bending element having a support in the form of a beam and end regions connected to said support via bending regions;            at least one counter electrode rigidly connected to one end region of the bending element, said counter electrode interacts with the measuring electrode positioned on the support, wherein both the measuring electrode and a reference capacitor having been applied in a planar manner along with an electronic component to a glass substrate fastened on the support, and both measurement data and an energy supply being available via connections.                        
The invention is based on the realization that a measuring element with a greater endurance and with improved overload resistance can be created by the use of an integrated capacitive microsystem in which both the measuring electrode and a reference capacitor are applied to a glass substrate by planar technology along with an electronic component. The sensor can be produced by known, tried-and-tested production technologies and equipment. The sensor can be used in particular for measuring a force when it has been mounted on a deforming element of known mechanical properties. For measuring a force, in particular the force of a weight on a vehicle seat, seat fastenings are designed as deforming elements, to which at least one capacitive microsystem for recording mechanical deformations is respectively attached.
It is particularly advantageous to make the data and/or energy transmission contactless. For this purpose, a capacitive microsystem is respectively equipped with an induction coil, so that data can be transmitted to the outside. At the same time, the capacitive microsystem can be supplied with energy from the outside via the induction coil.
For the interaction of a number of capacitive Microsystems at a number of fastening points of a vehicle seat, an induction loop taken via each capacitive microsystem is advantageously used.
The operating mode of a capacitive microsystem is advantageously set up in such a way that it alternates between energy transmission for the system and data transmission to the outside.